Ratings: The Big Bang Theory Dominates Over American Idol

American Idol's second Season 11 outing drew 18 million viewers, down from the 21.6 million who tuned in for the season premiere on Wednesday. Fox's reality series bested The Big Bang Theoryin total viewers (15.8 million), but the 100th episode of the CBS comedy scored a 5.3 in the coveted 18-49 demo, with Idol trailing at 5.2 during its first half-hour.

Overall, Idol was down 20 percent from the Wednesday telecast, and down 28 percent from last season's first Thursday airing.